Mystra
Mystra is known as the Mother of all Magic and she has the divine duty of maintaining and protecting the Weave. While Boccob is interested in finding new ways to use the energies of the weave in the planes, Mystra concerns herself first and foremost with the Weave itself. Unbeknownst to most except her followers, the name Mystra has actually functioned as more of a title, the name of a powerful divine force that has changed hand between sorceresses and powerful mages since the beginning. The prime iteration was known as Mystryl, and was destroyed in a disaster on the material plane in its infancy (orchestrated by Shar) that sent shock-waves through the Weave and caused the destruction of the Arcanists' Pantheon. The last iteration of Mystra was slain by the god Helm, who had been infected with the madness of Cyric. The newest to hold the title of Mystra was chosen by the entity after several decades had passed, and was formerly known as Midnight. Relationships Mystra as a divine power has knowledge that spans back to the beginning of time, and each new Mystra is aware of what had happened previously to the others. Mystra works closely with Oghma from time to time, and also works with Gond but the two are highly competitive. She is also a close ally to Milil and Deneir. Mystra is served by Azuth, Savras, and Velsharoon. As Midnight, Mystra had once been a companion to both Cyric and Kelemvor, the latter of the two being her consort. Mystra is a tentative ally of Wee Jas, and has knowledge of Boccob, but she never puts too much trust in either, as either one could attempt to make themselves the prime deity of magic, but none could handle the weave as she can. Before being killed by Helm, the last iteration had been held prisoner by Bane and tortured for weeks. This memory is very fresh in the mind of the entity. Talos is a constant threat to Mystra's worshipers, taking any opportunity to sabotage their rituals. The Division of Power A fact only known to Mystra and a handful of others is that she is in all actuality capable of being the most powerful being in the planes, and may already be so. This comes with a lot of danger and constant fear, or at least it did. Two iterations ago the divine being that is Mystra formulated a plan to divide the power of the entity into smaller pieces. This works as a solution to two problems. Firstly the separation ensures that her next incarnation appears in a timely manner, since there's always a good amount of Mystra's energy in the multiverse at any given moment. It also ensures that her power is kept constantly in check and never exceeds what would be considered an excessive level, as any huge spike in power would garner unwanted attention that could bring danger within range of the weave. The first division of power was created with the demigods Azuth and Savras, who were directly sponsored by her power. The second division came in the form of children she had in the material planes, most of which are immortal casters that have reached godlike status throughout their worlds. They serve as the leaders for her primary church, the Church of Mysteries. Worship of Mystra The holy symbol of Mystra's clergy has changed with each new iteration at the Goddess's request, and due to the potential for serious changes to her likeness and attitude the church does not use a specific set of statues or effigies, nor does it have a book of laws that are impossible to amend if necessary (the iterations of the goddess have often raised and lowered restrictions on what forms of magic are possible in the planes). One of the primary duties of the church is to bring proper healthcare and treatment to those who have been permanently injured by magic (things like accidental mind-wipes and limbs that have been torn off). There is also a small branch of Mystra's followers that are devoted purely to visiting every church of Mystra and ensuring their rules are up to date, as well as doing some close inspections. In recent years churches of Shar and Cyric have sprouted up in small villages, pretending to be churches of the mother of magic, but actually teaching ways to access the Shadow Weave.